The reason why Weyl and Dirac semimetals also have been fascinating is due to some intriguing properties that are absent in conventional metals. Some examples include the anomalous Hall [1]}, [2]} and Nernst [3]}, [4]}, [5]} effects, open Fermi arcs [6]}, planar Hall and Nernst effects [7]}, [8]}, and the manifestation of chiral or Adler-Bell-Jackiw anomaly [9]}, [10]}, [11]}, [12]}, [13]}, [14]}, [14]}, [16]}, [17]}, [18]}, [19]}. The origin of each of these effects can be traced down to the non-trivial topology of the Bloch bands. Specifically, the low-energy bandstructure of Weyl nodes comprise of pairs of non-degenerate massless Dirac cones that are topologically protected by the chirality quantum number (also known as the Chern number). Without any coupling to an external gauge field, the charge of a given chirality remain conserved. The conservation law is however broken when Weyl fermions are coupled to background gauge fields such as electric or magnetic fields [9]}, [10]}, [11]}. This breakdown of conservation laws is known as `chiral anomaly', rooting its name from the particle physics literature. The verification of chiral anomaly in Weyl semimetals is a very active area of investigation in condensed matter physics.
